Jump to content
The mkiv Supra Owners Club

weird problem after changing gear loses power?


muzzytt

Recommended Posts

car runs fine, If I boost it through say first gear I grab second and it loses the urge to keep going for a couple of seconds even the exhaust sound changes then it clears up and away we go !

 

Ive cleaned the filter of the VVTI solenoid but cant rule that out .

 

It almost always does it if I change gear after the second turbo has cone online

If I change gears before 3800 this problem doesn't happen

 

The car is fitted with blitz boost controller not sure if that's fitted correctly as ive just purchased the car!

Link to comment
Share on other sites

Does sound like either the settings on the boost controller are wrong (have a look at the gain, if its set too high it might cause these symptoms. When do the turbos come online? Does it feel different to a stock?) or as said, it could be a vsv. Probably the egcv as it might not be spooling the second turbo properly. Do you get a problem during say a 3rd gear pull when both should come online or only when changing gear?

 

Just thought, it also might be the pressure tank not holding pressure as it should.

Link to comment
Share on other sites

Just driving home after work I was in second gear I held second gear on quarter throttle when tacho reached 3800-4000 rpm the exhaust note changed and car seemed lethargic till revs dropped back down.

 

I will get some more info on the boost controller and some pics of how its setup etc

 

Thanks for suggestions so far

Edited by muzzytt (see edit history)
Link to comment
Share on other sites

ok here is a pic of the boost controller and how its connected.

I got pics of the egvc , also have good coating of oil in the intake and the pressurised pipes . I do think I had a bad pcv vlave wich i recently replaced with a new one.

 

anyway back to this turbo issue and checked some of the pipes no slpits but its easy to spin some of them so theres possible leakage ?

 

image

image

 

intake pipe going to turbo inlets

 

image

 

image

Link to comment
Share on other sites

Re the boost controller. . The out is connected to one pipe going directly top the pressure tank under manifold, the. Actuators of the Turbos wastegate.

Is this proper way of connecting?

 

Also tested the two vsv Ay the front of engine with ohm meter all good also applied 12v and both work properly. Also did the same with the one right at the top near cam cover that's also good.

I applied compressed air to egvc and the arm operates in and out.

Link to comment
Share on other sites

Just driving home after work I was in second gear I held second gear on quarter throttle when tacho reached 3800-4000 rpm the exhaust note changed and car seemed lethargic till revs dropped back down.

 

 

That sounds like your Exhaust Gas Control Valve isn't opening. It's supposed to open around those rpms to let exhaust gas flow through the second turbo. If it doesn't, the 2nd tubby doesn't spin, and the boosted air from turbo #1 goes back out to atmosphere through the compressor side of turbo #2. You lose all boost, the engine goes flat.

 

See here:

http://www.mkivsupra.net/vbb/showthread.php?35926-The-sequential-system

Link to comment
Share on other sites

That sounds like your Exhaust Gas Control Valve isn't opening. It's supposed to open around those rpms to let exhaust gas flow through the second turbo. If it doesn't, the 2nd tubby doesn't spin, and the boosted air from turbo #1 goes back out to atmosphere through the compressor side of turbo #2. You lose all boost, the engine goes flat.

 

See here:

http://www.mkivsupra.net/vbb/showthread.php?35926-The-sequential-system

 

thats exactly how it feels. I think problem is intermittent and as car generally pulls hard problem only really happens when I back off throttle change gear its at this point the symptoms usually appear for a few seconds then you can hear it fix itself as the noise goes back to how it normally is .

like i stated in an above post I tested the egvc with some comnpressed air and it freely moves in and out so that rules a mechanical issue with the actual valve. I also tested the vsv that feeds it and its is within spec, i also applied 12v to it and it opens and closes as it should.

 

so the issue is furher up the line .

 

I gotto verify if the boost controller is connected properly .

Link to comment
Share on other sites

I think my blitz SBC-ID II is installed wrong . according to mkiv technical articles the vsv needs both ports capped off and one of the outlets of the wastegate actuator needs to be capped off.(on mine all this is still connected up) looking at my picture above theyve used the old BOVs old connection line as the out connection (pressure reading is taken off this ) and the in is connected to the top of the no1 turbo wastegate actuator .

maybe this is causing loss of pressure in the pressure tank that is causing what i describe above.hmmm

definetly doesnt look correct ...

Edited by muzzytt (see edit history)
Link to comment
Share on other sites

update

 

Someone has disconnected the IN pipe to the pressure tank and put a screw in it to cap it off. Then they have put another line top the pressure tank wich then connects to the old bov line wich is then T'd to the pressure outlet in the Y pipe. You can see this in the picture above.!

 

Ive reconnected the pressure tank the way its suppose to be. Currently plumbing the EBC the way its described in the mkiv site..

Link to comment
Share on other sites

Yeah im hoping I just dont understand why they went top all that trouble?

Essentially they were getting pressure reading directly from the IN port of the pressure tank!

Im still tidying some areas like the intercooler pipe that was hitting the hole in the chassis.

All the vibration against the chassis was eating into the intercooler pipe. It's common on these aftermarket coolers the hole is not big enough.

 

Thanks for the ideas guys plus lots of research teaches alot!

Link to comment
Share on other sites

car feels much better THOUGH Ive hit a problem

 

Im running the blitz sbc id3 and even with settings at zero once second turbo kicks in ive hit 20psi !!! Ive double checked the plumbing I have the pipe from the turbo pressure out nipple going to the solenoids IN and the pipe from the wastegate actuator going to the OUT of the solenoid.

 

the first turbo is boosting to 10-11 psi but once we reach 3800 and the second turbo kicks in it just goes off the scale hitting 19 psi even though settings are at 0 on the controller

 

hmm I must have missed something , so what controls the boost of the second turbo ?

Link to comment
Share on other sites

That's sorted bloody cap on wastegate came off!

 

Now that everything is hooked up correctly ive tested the pressure tank by removing one of the

hoses and no air is heard hissing out does this mean the tank is failed? Ive tested right after a run.

The issue is the second turbo does come online its this sound change and flatness after a gear change say at 4000 rpm

Link to comment
Share on other sites

ive tested the pressure tank by taking off a hose on the iacv valve vsv and i did hear a hiss of air for about 2-3 seconds does this sound normal guys ?

 

Sounds about right. It doesn't need to hold much pressure, just enough to push the valves open once or twice when off boost.

Link to comment
Share on other sites

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.
Note: Your post will require moderator approval before it will be visible.

Guest
Reply to this topic...

×   Pasted as rich text.   Restore formatting

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.

×
×
  • Create New...

Important Information

We have placed cookies on your device to help make this website better. You can adjust your cookie settings, otherwise we'll assume you're okay to continue. You might also be interested in our Guidelines, Privacy Policy and Terms of Use.